CN111378593A

CN111378593A - Microbial inoculum for preparing fermented vegetable protein beverage

Info

Publication number: CN111378593A
Application number: CN201811621359.5A
Authority: CN
Inventors: 焦琳; 郑晓卫; 陈博; 杨洁; 申彤; 陈红征; 岳海涛
Original assignee: Xinjiang University; Cofco Nutrition and Health Research Institute Co Ltd
Current assignee: Xinjiang University; Cofco Nutrition and Health Research Institute Co Ltd
Priority date: 2018-12-28
Filing date: 2018-12-28
Publication date: 2020-07-07
Anticipated expiration: 2038-12-28
Also published as: CN111378593B

Abstract

The microbial inoculum comprising the strain of lactobacillus paracasei LCX25 and the strain of lactococcus lactis subsp. lactis LL9 of the invention can keep the flavor of the raw material and increase the milk flavor of the raw material when fermenting the raw material of vegetable protein slurry to prepare a fermented vegetable protein beverage; moreover, because the number of viable bacteria obtained by fermenting the microbial inoculum is high, the fermentation can be completed in a short time, and the production cost is saved; in addition, the bacterial strain in the microbial inoculum does not contain virulence genes, belongs to a safe bacterial strain, and is novel bovine-derived lactobacillus paracasei and lactococcus lactis subspecies lactis which are suitable for the field of vegetable protein beverage fermentation.

Description

Microbial inoculum for preparing fermented vegetable protein beverage

Technical Field

The invention relates to a microbial inoculum for preparing fermented beverage, in particular to a microbial inoculum for preparing fermented vegetable protein beverage, a preparation method and application of the microbial inoculum, and the fermented vegetable protein beverage prepared from the microbial inoculum.

Background

According to the regulation of GB10789-2007 rules of beverages 5.3.2 "vegetable protein beverages", vegetable protein beverages refer to milky beverages (hence sometimes referred to as "vegetable milk beverages") prepared by adding water or other food ingredients to a processed (i.e., fermentable by lactic acid bacteria) slurry, using as a raw material a vegetable fruit, seed or nut (e.g., soybean, peanut, almond, walnut kernel, coconut, etc.) having a certain protein content, and belong to the protein beverages. The vegetable protein beverage is well received by consumers due to the characteristics of no cholesterol or less cholesterol, rich protein and amino acid, appropriate unsaturated fatty acid content, comprehensive nutrient components and the like. The vegetable protein beverage products can be classified into walnut juice (milk) beverage, almond juice (milk) beverage, peanut juice (milk) beverage, coconut juice (milk) beverage, soymilk (milk) beverage, composite vegetable protein beverage containing various vegetable proteins and the like according to different main raw materials used.

With the continuous improvement of the pursuit of people on the quality of life and the more and more strong demand on health, the people pay more attention to the nutritional and healthy effect brought by diet besides paying attention to the experience of delicacy. Compared with other beverages, the vegetable protein beverage has obvious advantages, has a more perfect nutritional structure than animal protein, and has more guarantee on raw material sources, so in recent years, low-fat and cholesterol-free vegetable protein resources are more and more favored by people.

The statistical data of the market demand and investment planning analysis report of the Chinese vegetable protein beverage industry in 2018-2023 of the prospective industry research institute show that the vegetable protein beverage is the fastest in acceleration of the beverage sub-industries since 2007, and the market scale of the vegetable protein beverage manufacturing industry in 2016 is the highest, so that the embodiment of health appeal in the aspect of diet of people can be seen; further, the market for this industry is expected to further increase in 2020 and remains a major subdivision of the beverage manufacturing industry.

Among these, for example, peanuts are rich in fat and protein, and have been determined to have a fat content of about 45%, a protein content of about 24-36%, and a sugar content of about 20%; in addition, peanuts are rich in vitamins and minerals, particularly amino acids essential to the human body, and therefore, peanuts are also called "peanut plants"; the peanuts are also rich in arachidonic acid and natural polyphenol resveratrol, and have the effects of antivirus, anti-inflammation, antibiosis and the like; in addition, linoleic acid contained in the peanuts can reduce the accumulation of cholesterol in the body, thereby reducing the incidence of various cardiovascular and cerebrovascular diseases caused by the accumulation of cholesterol. Meanwhile, the walnut has rich nutritive value and has various reputations of 'Wansui', 'Changshou', 'health preserving treasure' and the like; about 86% of fat in walnut is unsaturated fatty acid, and is rich in copper, magnesium, potassium, vitamin B6, folic acid, vitamin B1, etc., and also contains fiber, phosphorus, nicotinic acid, iron, vitamin B2, pantothenic acid, etc.; according to the determination, the water content of each 50 g of walnut accounts for 3.6 percent, and the walnut further contains 7.2 g of protein, 31 g of fat and 9.2 g of carbohydrate; research shows that the walnut can reduce the content of cholesterol in blood and reduce the incidence rate of coronary heart disease and other chronic diseases; the abundant omega-3 fatty acid in walnut can reduce the probability of suffering depression, Attention Deficit Hyperactivity Disorder (ADHD), cancer, senile dementia and the like, and can reduce the risk of suffering from breast cancer, tumor and gallstone in women.

On the other hand, the fermented vegetable protein beverage is a milk beverage prepared by fermenting a processed vegetable fruit, seed or kernel slurry with lactic acid bacteria. Similarly, depending on the main raw materials used, the beverage can be classified into fermented walnut milk (milk) beverage, fermented almond milk (milk) beverage, fermented peanut milk (milk) beverage, fermented coconut milk (milk) beverage, fermented soybean milk (milk) beverage, fermented composite vegetable protein beverage, and the like. Among them, for example, as an example of the fermentation type composite vegetable protein beverage, the fermentation type walnut peanut milk (milk) beverage is a product obtained by grinding peanuts and walnuts into slurry and inoculating lactic acid bacteria.

In this regard, the lactobacillus is an internationally recognized safe leavening agent, and extracellular polysaccharide generated by the lactobacillus during the fermentation of the vegetable protein beverage has good adsorption effect on heavy metals such as lead and the like, and has the effects of resisting tumor, resisting oxidation, resisting aging, enhancing immunity and the like; in addition, the plant protein beverage does not produce lactose in the fermentation process, so the plant protein beverage is a good substitute for lactose intolerant people; moreover, the vegetable protein can not only make up the deficiency of the plant milk source of the public, but also fully degrade the protein after being fermented by lactic acid bacteria, thereby improving the digestibility and the nutritive value, and being an ideal health drink. However, as a product having the advantages of both a vegetable protein beverage and a yogurt probiotic beverage, research and development at present are not sufficient enough, and it is difficult to meet market demands.

On the other hand, although the vegetable protein beverage can obtain a special flavor due to fermentation after being fermented with lactic acid bacteria, the original flavor of the vegetable fruit, seed, or kernel (for example, soybean, peanut, almond, walnut kernel, coconut, etc.) is lost, and the taste is deteriorated. Therefore, the need still exists in the field of screening out a microbial inoculum which can not only retain the flavor of raw milk in the fermentation process, but also endow the fermentation product with unique lactobacillus fermentation flavor so as to solve the problem of taste loss of the fermentation type vegetable protein beverage. In addition, it would be desirable in the art to have a microbial inoculum for a fermented vegetable protein beverage that is simultaneously suitable for fermenting a variety of vegetable milk sources, such as peanuts and walnuts.

Disclosure of Invention

In order to solve the above problems, the present inventors have screened and analyzed various lactic acid bacteria that can be used for fermenting a vegetable protein beverage to obtain a fermented vegetable protein beverage, and have surprisingly found that a fermented vegetable protein beverage that retains the flavor of the raw milk itself and exhibits a unique lactic acid bacteria fermentation flavor can be obtained by fermenting a raw material slurry containing vegetable protein with a microbial inoculum comprising two specific strains, thereby completing the present invention.

Therefore, in a first aspect, the present invention provides a microbial inoculum for preparing a fermented vegetable protein beverage, which comprises an LCX25 strain and an LL9 strain, wherein the LCX25 strain is classified as Lactobacillus paracasei (Lactobacillus paracasei), which is deposited at the common microorganism center of the collection and management committee of chinese microbial cultures (CGMCC) 11/6 th 2018 (No. 3, institute of microbiology, china academy of sciences, north chen sunward, tokyo city, No. 3 of west way 1 of north chen, No.16713 of china institute of microbiology); the LL9 strain is classified as Lactococcus Lactis subsp Lactis (CGMCC), which is deposited in China general microbiological culture Collection center (CGMCC) at 11 and 6 months in 2018 (No. 3 of the institute of microbiology, China institute of sciences, Ministry of sciences, North Chen West Lu No.1 of the Inward region in Beijing), and the deposited number is CGMCC No. 16714.

Preferably, the fermented vegetable protein beverage is a fermented walnut milk beverage, a fermented almond milk beverage, a fermented peanut milk beverage, a fermented coconut milk beverage, a fermented soymilk beverage or a fermented composite vegetable protein beverage; more preferably, the fermented vegetable protein beverage is a fermented walnut milk beverage, a fermented peanut milk beverage or a fermented walnut peanut milk beverage.

Preferably, the microbial inoculum comprises the LCX25 strain and the LL9 strain in a ratio of 1:10 to 10:1, preferably 1:8 to 8:1, more preferably 1:5 to 5:1, further preferably 1:3 to 3:1, particularly preferably 1:2 to 2:1, most preferably 1:1, but the present invention is not limited thereto.

Preferably, the agent is in the form of a lyophilized powder, but the present invention is not limited thereto.

In a second aspect, the present invention provides a method for preparing the microbial inoculum for preparing the fermented vegetable protein beverage according to the first aspect, wherein the method comprises the following steps:

(1) respectively inoculating the LCX25 strain and the LL9 strain into a seed culture medium, and culturing at the temperature of 30-37 ℃ and the rotation speed of 180-200rpm for 12-24h to obtain a seed culture solution;

(2) respectively inoculating the seed culture solution obtained in the step (1) into a sterilized fermentation culture medium, continuously fermenting at the temperature of 30-37 ℃ at the rotation speed of 180-200rpm for 12-24h, and maintaining the pH of fermentation liquor at 5-7 in the fermentation process to obtain strain fermentation liquor, wherein the seed culture solution is respectively inoculated into the fermentation culture medium in a ratio of 1-2 v/v%;

(3) centrifuging the strain fermentation liquor obtained in the step (2) and collecting bacterial sludge to respectively obtain bacterial sludge of the LCX25 strain and bacterial sludge of the LL9 strain;

(4) and (3) mixing the bacterial sludge of the LCX25 strain and the bacterial sludge of the LL9 strain to obtain the microbial inoculum for preparing the fermented vegetable protein beverage.

Preferably, the seed culture medium and the fermentation medium are MRS liquid culture medium.

Preferably, in step (3), the centrifugation is performed at 4000-.

Preferably, the method further comprises the steps of: after the step (3) and before the step (4), adding a protective agent according to the volume ratio of the bacterial sludge to the protective agent 1 (3-5), fully mixing, pre-freezing overnight at-80 ℃, and preparing freeze-dried powder by vacuum freeze-drying; more preferably, the protective agent is selected from one or more of trehalose, sodium glutamate, skim milk and glycerol, and further preferably, the protective agent is a mixture of trehalose, sodium glutamate, skim milk and glycerol in equal volume.

Preferably, in step (4), the puree of the LCX25 strain and the puree of the LL9 strain are mixed in a ratio of 1:10 to 10:1, preferably 1:8 to 8:1, more preferably 1:5 to 5:1, further preferably 1:3 to 3:1, particularly preferably 1:2 to 2:1, most preferably 1: 1.

In a third aspect, the invention provides the use of the microbial inoculum for preparing the fermented vegetable protein beverage in the first aspect in preparing the fermented vegetable protein beverage.

Preferably, the number of viable bacteria in the prepared fermented vegetable protein beverage is 10¹⁰cfu/mL-10¹²cfu/mL, more preferably 2 × 10¹⁰cfu/mL-5×10¹¹cfu/mL, more preferably 4 × 10¹⁰cfu/mL-2.5×10¹¹cfu/mL, particularly preferably 8 × 10¹⁰cfu/mL-1.25×10¹¹cfu/mL, most preferably 10¹¹The amount of cfu/mL comprises the LCX25 strain and the LL9 strain.

In a fourth aspect, the invention provides a fermented vegetable protein beverage prepared by using the microbial inoculum for preparing the fermented vegetable protein beverage according to the first aspect.

Preferably, the number of viable bacteria in the prepared fermented vegetable protein beverage is 10¹⁰cfu/mL-10¹²cfu/mL, more preferably 2 × 10¹⁰cfu/mL-5×10¹¹cfu/mL, more preferably 4 × 10¹⁰cfu/mL-2.5×10¹¹cfu/mL, particularly preferably 8 × 10¹⁰cfu/mL-1.25× 10¹¹cfu/mL, most preferably 10¹¹The amount of cfu/mL comprises the LCX25 strain and the LL9 strain.

Advantageous effects

Other features and advantages of the present invention will be described in detail in the following detailed description.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The microbial inoculum can be used for preparing various fermented vegetable protein beverages, and the obtained fermented vegetable protein beverage can not only retain the flavor of raw milk, but also present unique lactobacillus fermentation flavor. In some preferred embodiments of the present invention, the fermented vegetable protein beverage is a fermented walnut milk beverage, a fermented almond milk beverage, a fermented peanut milk beverage, a fermented coconut milk beverage, a fermented soymilk beverage or a fermented composite vegetable protein beverage. In some more preferred embodiments of the present invention, the fermented vegetable protein beverage is a fermented walnut milk beverage, a fermented peanut milk beverage, or a fermented walnut peanut milk beverage. However, the present invention is not limited thereto.

Various vegetable protein-containing raw material slurries (e.g., slurries of soybean, peanut, almond, walnut kernel, coconut, etc., or mixed slurries thereof) for fermenting them to prepare fermented vegetable protein beverages can be prepared by conventional methods in the art.

In the present invention, the terms "vegetable protein drink" and "vegetable milk drink" are used interchangeably; the terms "milk beverage", "dew beverage" and "juice beverage" may also be used interchangeably depending on the plant material. Also, in the present invention, the terms "fermented vegetable protein beverage" and "fermented vegetable milk beverage" may be used interchangeably; the terms "fermented milk drink", "fermented dew drink" and "fermented juice drink" may also be used interchangeably depending on the plant material.

The ratio of the strain of lactobacillus paracasei LCX25 and the strain of lactococcus lactis subsp lactis LL9 in the microbial agent of the present invention is not particularly limited, and in some preferred embodiments of the present invention, the microbial agent of the present invention may comprise the LCX25 strain and the LL9 strain in a ratio of 1:10 to 10:1, preferably 1:8 to 8:1, more preferably 1:5 to 5:1, further preferably 1:3 to 3:1, particularly preferably 1:2 to 2:1, most preferably 1: 1. However, the present invention is not limited thereto.

The microbial inoculum can be in a liquid form or a solid form, and can be in a freeze-dried powder form for the purposes of storage and use. However, the present invention is not limited thereto.

The seed culture solution and the strain fermentation liquid of the microbial inoculum can be prepared by using a standard culture method of lactic acid bacteria. For example, the seed culture solution can be prepared by the following process: single colonies of the L.paracasei LCX25 strain and the L.lactis subspecies lactis LL9 strain are picked from the plate and respectively inoculated into an MRS liquid culture medium serving as a seed culture medium, and the culture is carried out for 12 to 24 hours at the rotation speed of 180-200rpm at the temperature of between 30 and 37 ℃ to obtain a seed culture solution. For example, the strain fermentation broth may be prepared by the following process: respectively inoculating the seed culture solution of the microbial inoculum of the invention into a sterilized MRS liquid culture medium which is used as a fermentation culture medium and is placed in a fermentation tank, continuously fermenting for 12-24h at 30-37 ℃ and at the rotation speed of 180-200rpm, and maintaining the pH of the fermentation liquid to be 5-7 in the fermentation process to obtain strain fermentation liquid, wherein the seed culture solution is respectively inoculated into the MRS liquid culture medium at the ratio of 1-2 v/v%. However, the present invention is not limited thereto, and those skilled in the art can select appropriate methods and reagents for preparing seed culture broth and strain fermentation broth of the microbial inoculum of the present invention.

The strain fermentation liquid obtained from the LCX25 strain and the LL9 strain has higher viable count, and can be directly subjected to vacuum freeze drying to obtain the freeze-dried powder of the microbial inoculum. Preferably, the strain fermentation liquid is centrifuged at 4000-. Preferably, the protective agent is added according to the volume ratio of the bacterial sludge to the protective agent of 1 (3-5), the mixture is fully mixed and then is pre-frozen at minus 80 ℃ overnight (for example, 8-12h), and the mixture is frozen and dried in vacuum to prepare the freeze-dried powder. Preferably, the protective agent can be selected from one or more of trehalose, sodium glutamate, skim milk and glycerol; more preferably, the protectant is a mixture of equal volumes of trehalose, sodium glutamate, skim milk and glycerol.

The microbial inoculum of the present invention comprising the strain lactobacillus paracasei LCX25 and the strain lactococcus lactis l9 can be used to ferment a variety of vegetable protein slurry substrates including, but not limited to, walnut milk, almond milk, peanut milk, coconut milk, soy milk, or a complex vegetable milk (such as, but not limited to, walnut peanut milk) to provide a fermented walnut milk (milk) beverage, a fermented almond milk (milk) beverage, a fermented peanut milk (milk) beverage, a fermented coconut milk (milk) beverage, a fermented soy milk (milk) beverage, or a fermented complex vegetable protein beverage (such as, but not limited to, a fermented walnut peanut milk beverage), and the like. In some preferred embodiments of the invention, the microbial inoculum of the invention is used for fermenting walnut milk and/or peanut milk, so as to obtain a fermented walnut juice (milk) beverage, a fermented peanut juice (milk) beverage or a fermented walnut peanut juice (milk) beverage.

In some preferred embodiments of the present invention, the number of viable bacteria in the fermented vegetable protein beverage is 10¹⁰cfu/mL-10¹²cfu/mL, more preferably 2 × 10¹⁰cfu/mL-5× 10¹¹cfu/mL, more preferably 4 × 10¹⁰cfu/mL-2.5×10¹¹cfu/mL, particularly preferably 8 × 10¹⁰cfu/mL-1.25×10¹¹cfu/mL, most preferably 10¹¹The amount of cfu/mL comprises the LCX25 strain and the LL9 strain. In some preferred embodiments of the present invention, in case the microbial inoculum of the present invention is lyophilized powder, it can be in the range of, for example, 0.01-0.1g lyophilized powder/100 mL, including, for example, 0.02g lyophilized powder/100 mL, 0.04g lyophilized powder/100 mL, 0.06g lyophilized powder/100 mL, or 0.0g lyophilized powderThe freeze-dried powder of the microbial inoculum of the invention is directly added into plant protein slurry substrates (such as sterile peanut milk and walnut milk) at the concentration of 8g freeze-dried powder/100 mL, as long as the viable count is ensured to be within the range.

Examples

The present invention will be described in further detail with reference to examples, but the present invention is not limited to these examples. In the following examples, reagents and media used are commercially available unless otherwise specified, and the methods used are conventional.

The MRS liquid medium used in the examples was: 10.0g of peptone, 5.0g of yeast extract powder, 10.0g of beef extract, 20.0g of glucose, 2.0g of dipotassium phosphate, 2.0g of diammonium citrate, 5.0g of anhydrous sodium acetate, 0.25g of manganese sulfate, 0.58g of magnesium sulfate and 801.0 mL of Tween, supplementing distilled water to 1000mL of final volume, adjusting the pH to 5-7, and sterilizing at 121 ℃ for 15-20 min; the MRS solid medium (plate) used in the examples was: to 1000mL of MRS liquid medium prepared as described above, 18g of agar was added, and autoclaved after adjusting pH to 5-7.

In the embodiment, the yoghurt prepared by traditional fermentation of Xinjiang herdsmen is used as a sample source, and the yoghurt is collected from the self-made yoghurt of herdsmen in Xinjiang karshi pasturing areas and stored at-80 ℃.

Example 1 isolation, screening and characterization of Lactobacillus paracasei LCX25 Strain and lactococcus lactis subsp

The preparation method comprises the steps of taking yoghurt prepared by traditional fermentation of Xinjiang herdsmen as a sample source, coating yoghurt diluent on an MRS solid culture medium by adopting a gradient dilution method, culturing for 24-48h at 30-37 ℃, and purifying by a plate-scribing method to obtain a plurality of single colonies. Culturing and activating each single colony in an MRS liquid culture medium, taking 2 mu L of activated bacterial liquid, dibbling the bacterial liquid to the surface of an MRS solid culture medium containing 1 w/v% of calcium carbonate, observing the diameter of a calcium melting ring, and screening strains with high lactic acid production capacity. Then, a gradient dilution method is adopted again, single colonies with large calcium-dissolving rings are picked and repeatedly streaked on an MRS solid culture medium, the single colonies are cultured for 24-48h at the temperature of 30-37 ℃ until the colonies are completely consistent in color, size and shape, the single colonies after purification are transferred to an MRS liquid culture medium for amplification culture, and the strains obtained by purification culture are named as an LCX25 strain and an LL9 strain respectively.

Morphological identification and 16s rDNA identification of the strain:

(1) morphological identification: the LCX25 bacterial strain presents white round convex opaque bacterial colony on MRS solid culture medium, presents straight or bent rod shape under microscope, and presents chain arrangement singly or in pairs, which accords with the basic morphological characteristics of lactobacillus paracasei; LL9 strain appears as white round convex opaque colony on MRS solid culture medium, appears as round or oval sphere under microscope, is arranged in pairs or chains, and accords with the basic morphological characteristics of lactococcus lactis subspecies lactis.

(2)16s rDNA identification: genomic DNA of LCX25 strain and LL9 strain were extracted, and the 16s rDNA sequence was sequenced as shown in SEQ ID No.1 and SEQ ID No. 2. The obtained 16s rDNA sequence was compared with the NCBI database, and it was found that the LCX25 strain had the highest homology with Lactobacillus paracasei JCM1171 (GenBank: D16550.1) (the sequence identity of the 16s rDNA sequence of LCX25 strain with the 16s rDNA sequence of Lactobacillus paracasei JCM1171 was 99.93%); the LL9 strain had the highest homology to lactococcus lactis JCM5805(T) (GenBank: BALX01000047.1) (the sequence identity of the 16s rDNA sequence of the LL9 strain to the 16s rDNA sequence of lactococcus lactis JCM5805(T) was 99.04%).

Based on the above morphological identification and 16s rDNA identification results, it was finally determined that the LCX25 strain and the LL9 strain belong to Lactobacillus paracasei (Lactobacillus paracasei) and Lactobacillus Lactis subsp Lactis (Lactobacillus Lactis subsp Lactis), respectively.

Wherein, the LCX25 strain is preserved in China general microbiological culture Collection center (CGMCC) (No. 3 of West Lu No.1 of Beijing city Kogyo Kyoho, China academy of sciences microbiological research institute) at 11 months and 6 days in 2018, and the preservation number is CGMCC No. 16713; the LL9 strain is preserved in China general microbiological culture Collection center (CGMCC) at 11 months and 6 days in 2018 (No. 3 of Xilu-1 of Beijing, Chaoyang, China academy of sciences, institute of microbiology), and the preservation number is CGMCC No. 16714.

SEQ ID NO.1

CTCGCTCCCTAAAAGGGTTACGCCACCGGCTTCGGGTGTTACA AACTCTCATGGTGTGACGGGCGGTGTGTACAAGGCCCGGGAACGTA TTCACCGCGGCGTGCTGATCCGCGATTACTAGCGATTCCGACTTCGT GTAGGCGAGTTGCAGCCTACAGTCCGAACTGAGAATGGCTTTAAGA GATTAGCTTGACCTCGCGGTCTCGCAACTCGTTGTACCATCCATTGT AGCACGTGTGTAGCCCAGGTCATAAGGGGCATGATGATTTGACGTCA TCCCCACCTTCCTCCGGTTTGTCACCGGCAGTCTTACTAGAGTGCCC AACTAAATGCTGGCAACTAGTCATAAGGGTTGCGCTCGTTGCGGGA CTTAACCCAACATCTCACGACACGAGCTGACGACAACCATGCACCA CCTGTCATTTTGCCCCCGAAGGGGAAACCTGATCTCTCAGGTGATCA AAAGATGTCAAGACCTGGTAAGGTTCTTCGCGTTGCTTCGAATTAAA CCACATGCTCCACCGCTTGTGCGGGCCCCCGTCAATTCCTTTGAGTT TCAACCTTGCGGTCGTACTCCCCAGGCGGAATGCTTAATGCGTTAGC TGCGGCACTGAAGGGCGGAAACCCTCCAACACCTAGCATTCATCGT TTACGGCATGGACTACCAGGGTATCTAATCCTGTTCGCTACCCATGCT TTCGAGCCTCAGCGTCAGTTACAGACCAGACAGCCGCCTTCGCCAC TGGTGTTCTTCCATATATCTACGCATTTCACCGCTACACATGGAGTTC CACTGTCCTCTTCTGCACTCAAGTTTCCCAGTTTCCGATGCGCTTCC TCGGTTAAGCCGAGGGCTTTCACATCAGACTTAAAAAACCGCCTGC GCTCGCTTTACGCCCAATAAATCCGGATAACGCTTGCCACCTACGTA TTACCGCGGCTGCTGGCACGTAGTTAGCCGTGGCTTTCTGGTTGGAT ACCGTCACGCCGACAACAGTTACTCTGCCGACCATTCTTCTCCAACA ACAGAGTTTTACGACCCGAAAGCCTTCTTCACTCACGCGGCGTTGC TCCATCAGACTTGCGTCCATTGTGGAAGATTCCCTACTGCTGCCTCC CGTAGGAGTTTGGGCCGTGTCTCAGTCCCAATGTGGCCGATCAACCT CTCAGTTCGGCTACGTATCATCGCCTTGGTGAGCCATTACCTCACCA ACTAGCTAATACGCCGCGGGTCCATCCAAAAGCGATAGCTTACGCCATCTTTCAGCCAAGAACCATGCGGTTCTTGGATCTATGCGGTATTAGCA TCTGTTTCCAAATGTTATCCCCCACTTAAGGGCAGGTTACCCACGTG TTACTCACCCGTCCGCCACTCGTTCCATGTTGAATCTCGGTGCAAGCACCGATCATCAACGAGAACTCGTTCGACTG

SEQ ID NO.2

GGGCCGGGGCGGCGTGCTATACATGCAAGTTGAGCGCTGAAGG TTGGTACTTGTACCGACTGGATGAGCAGCGAACGGGTGAGTAACGC GTGGGGAATCTGCCTTTGAGCGGGGGACAACATTTGGAAACGAATG CTAATACCGCATAAAAACTTTAAACACAAGTTTTAAGTTTGAAAGAT GCAATTGCATCACTCAAAGATGATCCCGCGTTGTATTAGCTAGTTGG TGAGGTAAAGGCTCACCAAGGCGATGATACATAGCCGACCTGAGAG GGTGATCGGCCACATTGGGACTGAGACACGGCCCAAACTCCTACGG GAGGCAGCAGTAGGGAATCTTCGGCAATGGACGAAAGTCTGACCGA GCAACGCCGCGTGAGTGAAGAAGGTTTTCGGATCGTAAAACTCTGT TGGTAGAGAAGAACGTTGGTGAGAGTGGAAAGCTCATCAAGTGAC GGTAACTACCCAGAAAGGGACGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGTCCCGAGCGTTGTCCGGATTTATTGGGCGTAAAGC GAGCGCAGGTGGTTTATTAAGTCTGGTGTAAAAGGCAGTGGCTCAA CCATTGTATGCATTGGAAACTGGTAGACTTGAGTGCAGGAGAGGAG AGTGGAATTCCATGTGTAGCGGTGAAATGCGTAGATATATGGAGGAA CACCGGTGGCGAAAGCGGCTCTCTGGCCTGTAACTGACACTGAGGCTCGAAAGCGTGGGGAGCAAACAGGATTAGATACCCTGGTAGTCCAC GCCGTAAACGATGAGTGCTAGATGTAGGGAGCTATAAGTTCTCTGTA TCGCAGCTAACGCAATAAGCACTCCGCCTGGGGAGTACGACCGCAA GGTTGAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGTGGA GCATGTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTT GACATACTCGTGCTATTCCTAGAGATAGGAAGTTCCTTCGGGACACG GGATACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTT GGGTTAAGTCCCGCAACGAGCGCAACCCCTATTGTTAGTTGCCATCA TTAAGTTGGGCACTCTAACGAGACTGCCGGTGATAAACCGGAGGAA GGTGGGGATGACGTCAAATCATCATGCCCCTTATGACCTGGGCTACA CACGTGCTACAATGGATGGTACAACGAGTCGCGAGACAGTGATGTT TAGCTAATCTCTTAAAACCATTCTCAGTTCGGATTGTAGGCTGCAAC TCGCCTACATGAAGTCGGAATCGCTAGTAATCGCGGATCAGCACGCC GCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTCACACCA CGGGAGTTGGGAGTACCCGAAGTAGGTTGCCTAACCGCAAGGAGG GCGCTCCTAAGTAAGACCCGTAGCCGG

Example 2 preparation of a bacterial preparation of the invention comprising the Strain of Lactobacillus paracasei LCX25 and lactococcus lactis subsp lactis LL9 (lyophilized powder form)

Preparing a seed culture solution: single colonies of the L.paracasei LCX25 strain and the L.lactis subspecies lactis LL9 strain obtained in example 1 were picked, inoculated into MRS liquid medium, and cultured at 30-37 ℃ at a rotation speed of 180-200rpm for 12-24 hours to obtain a seed culture solution.

Preparation of strain fermentation broth (expanded culture): adding MRS liquid culture medium into a fermentation tank, sterilizing at 121 ℃ for 20min, cooling to 30-37 ℃ after sterilization, respectively adding the seed culture solution according to the proportion of 1-2 v/v%, continuously fermenting at 30-37 ℃ at the rotation speed of 180-200rpm for 24h, and maintaining the pH value of the fermentation liquid at 5-7 in the fermentation process to obtain the strain fermentation liquid.

The preparation of the freeze-dried powder of the microbial inoculum comprises the following steps: centrifuging the strain fermentation liquid at 4000-; adding a protective agent (a mixture of trehalose, sodium glutamate, skim milk and glycerol with the same volume) according to the volume ratio of the bacterial sludge to the protective agent of 1 (3-5); mixing, pre-freezing at-80 deg.C overnight (for example 8-12 hr), and vacuum freeze-drying to obtain lyophilized powder. When raw material slurry containing vegetable protein is fermented, freeze-dried powders of the two strains are mixed for use.

Example 3 determination of acid-producing ability of Lactobacillus paracasei LCX25 Strain and Lactobacillus lactis subsp

Activating strains: single colonies of the L.paracasei LCX25 strain and the L.lactis subspecies lactis LL9 strain obtained in example 1 were picked and inoculated into MRS liquid medium, respectively, and cultured at 30-37 ℃ at a rotation speed of 180-200rpm for 12-24 hours to obtain a bacterial liquid.

Detection of acid-producing ability: inoculating 2 mu L of bacterial liquid to the surface of an MRS solid culture medium containing 1 w/v% of calcium carbonate by adopting an inoculation method, culturing for 24-48h at 30-37 ℃, and measuring the diameter of a calcium dissolving ring to evaluate the acid production capacity of each strain. As a result, the diameter of the caldron of the strain Lactobacillus paracasei LCX25 can reach 26mm, while the diameter of the caldron of the strain lactococcus lactis subsp. lactis LL9 can reach 24mm, both of which have considerable acid-producing capacity.

Example 4 preparation of a fermented vegetable protein beverage Using the microbial inoculum of the invention comprising the strain Lactobacillus paracasei LCX25 and the Lactobacillus lactis subsp lactis LL9

Preparing peanut milk: removing impurities from fresh semen Arachidis Hypogaeae, parching at 100 deg.C for 15-20min, and kneading with wood plate to remove red skin to remove astringent taste of pigment and tannin on testa Arachidis Hypogaeae; adding the peanut kernels without red skins and washed cleanly by water into saturated salt solution at 30 ℃ for 1min according to the proportion of 1:2(w/v), and then adding the peanut kernels into 0.5% sodium bicarbonate aqueous solution at 100 ℃ for treatment for 20min according to the proportion of 1:15 (w/v); taking out, draining, and cleaning with clear water to remove attached alkali liquor; adding hot water with the mass of 15 times of that of the peanut kernels and the temperature of 80 ℃ to soak the peanut kernels, performing coarse grinding by a pulp grinder, and performing fine grinding by a colloid grinder to fully separate out protein and grease in tissues; then filtering the feed liquid through 300-mesh filter cloth to remove residues, stirring and dispersing the residues with water at 80 ℃, grinding, throwing residues and separating for 2 times to extract residual water-soluble protein in the residues; and combining the multiple filtrates, and mixing to obtain peanut milk.

Preparing walnut milk: selecting high-quality walnut kernels with plump meat quality, and rinsing with clear water to remove impurities; soaking 1kg Juglandis in 2L clear water for 4 hr, adding 4% sodium carbonate solution into the soaked Juglandis at a ratio of 1:15(w/v), boiling for 3min, and removing skin with high pressure water gun; cleaning with clear water and then drying; baking at 90 deg.C for 15min, adding distilled water into semen Juglandis at a ratio of 1:8(w/v), coarse grinding at 80 deg.C with a pulp grinder, and fine grinding with a colloid mill; filtering the filtrate with 200 mesh filter cloth, and grinding the residue for 2 times to increase protein yield; mixing the filtrates, and mixing to obtain walnut milk.

2.4L of each of the prepared peanut milk and walnut milk is taken and subpackaged into 200 mL/bottle, sterilized at the temperature of 116 ℃ for 5-10min, cooled to the temperature of 37-42 ℃, and inoculated into the sterile peanut milk and walnut milk respectively according to the inoculation proportion (weight to volume ratio) of 0.02 percent under the aseptic condition. Specifically, under the condition of separate inoculation, freeze-dried powder of the LCX25 strain and LL9 strain is respectively inoculated into sterile peanut milk and walnut milk, and the inoculation ratio is 0.02% (weight to volume); in the case of co-inoculation, the LCX25 strain and the LL9 strain were inoculated together with lyophilized powder into sterile peanut milk and walnut milk, respectively, at a mixed inoculation ratio of 1:1 and 3:1 for the LCX25 strain and the LL9 strain, and at a total inoculation ratio of 0.02% (weight to volume). Meanwhile, danisch YO-MIX611 (commercially available product) and kehansen YF903 (commercially available product) were used as controls, and inoculated into sterile peanut milk and walnut milk, respectively, at an inoculation ratio (weight to volume ratio) of 0.02% under the same aseptic conditions.

Mixing the peanut milk and the walnut milk inoculated with the microbial inoculum uniformly, standing at 42 ℃ for fermentation, stopping fermentation when the pH reaches 4.5, detecting the texture of the fermented milk, and carrying out sensory evaluation by experts (please refer to Wuxueshan, yogurt sensory evaluation and correlation study of the texture [ J ]. Chinese Dairy industry, 2015, 43(10): 52-54.). The results of the detection and evaluation are shown in tables 1 to 4.

As can be seen from table 1-table 2, when the vegetable protein slurry raw material was fermented using the microbial agent of the present invention comprising the strain lactobacillus paracasei LCX25 and the strain lactococcus lactis subsp lactis LL9 (LCX25: LL 9: 1), the gel rupture strength of the resulting fermented vegetable protein beverage was 9.365g, the fiber drawing length was 9.301 mm, the hardness was 30.261g, the consistency was 634.360g/s, the viscosity was 222.530mPa · s, and the best curd effect was obtained in the shortest fermentation time, as compared to two competitive products, danisc YO-MIX611 and cohansen YF 903; after the plant protein slurry raw material is fermented by using the microbial inoculum (LCX25: LL 9: 3:1) containing the strain of lactobacillus paracasei LCX25 and the strain of lactococcus lactis LL9, relatively good curd effect is obtained in relatively short fermentation time; single strain fermentation (LCX25 strain only or LL9 strain only) and two competitive products Danisco-MIX 611 and Kehansen YF903 have longer fermentation time and poor curd effect.

Furthermore, as can be seen from tables 3-4, the two competitive products Danisco YO-MIX611 and Kehansen YF903 (viable count after fermentation for 7-9h is only 10)⁷-10⁸cfu/mL magnitude), when the microbial inoculum (LCX25: LL9 ═ 1:1) containing the strain of Lactobacillus paracasei LCX25 and the strain of lactococcus lactis subsp. lactis LL9 is used for fermenting the plant protein slurry raw material, the viable count can reach 1.8 × 10 after 6-7h of fermentation¹¹cfu/mL; when the microbial inoculum (LCX25: LL 9: 3:1) containing the strain of lactobacillus paracasei LCX25 and the strain of lactococcus lactis LL9 is used for fermenting the plant protein slurry raw material, the viable count can reach 10 after 8 hours of fermentation¹⁰cfu/mL. Namely, the microbial inoculum of the invention can complete fermentation in a short time, thereby saving production cost.

In addition, compared with two competitive products, danisch YO-MIX611 and kehansen YF903 (the obtained fermented vegetable protein beverage has no special fragrance, and the fragrance of the peanut or walnut per se disappears, and also generates a pasty mouthfeel), the fermented walnut milk beverage and the fermented peanut milk beverage obtained by fermentation using the microbial inoculum (LCX25: LL 9: 1 and LCX25: LL 9: 3:1) comprising the lactobacillus paracasei LCX25 strain and the lactococcus lactis l9 strain of the present invention are easy to enter the mouth and are fresh and cool in mouthfeel, have no burnt mouthfeel, and exhibit thick peanut taste and walnut taste, increase the fragrance of the raw material per se, and have richer mouthfeel. In contrast, LL9 strain alone had a slightly mushy mouthfeel after fermentation and caused a reduction in the intrinsic peanut or walnut flavor; and the single LCX25 strain has longer fermentation time, and the peanut flavor and the walnut flavor after fermentation are also weakened compared with the microbial inoculum of the invention.

It can be seen that the microbial inoculum comprising the strain of lactobacillus paracasei LCX25 and the strain of lactococcus lactis subsp. lactis LL9 of the present invention not only achieves more excellent effects in terms of curd effects, fermentation time, and mouthfeel of the resulting fermented vegetable protein beverage than the existing commercially available products, but also achieves unexpected synergistic effects by combining the strain of lactobacillus paracasei LCX25 and the strain of lactococcus lactis subsp. lactis LL 9.

TABLE 1 fermentation time and texture of fermented walnut milk beverages

TABLE 2 fermentation time and texture of fermented peanut milk beverage

TABLE 3 sensory evaluation results of fermented walnut milk beverages

TABLE 4 sensory evaluation results of peanut milk beverages

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various modifications may be made to the technical solution of the present invention within the technical spirit of the present invention, and these modifications are within the protective scope of the present invention.

Sequence listing

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Claims

1. A microbial inoculum for preparing a fermented vegetable protein beverage, the microbial inoculum comprising LCX25 strain and LL9 strain, wherein,

the LCX25 strain is classified as Lactobacillus paracasei (Lactobacillus paracasei), which is preserved in China general microbiological culture Collection center (CGMCC) 11 and 6 days 2018 (No. 3 of Xilu 1 of Beijing Kogyo-oriented areas, China academy of sciences microbiological research institute) in the 11 th and 6 th months, and the preservation number is CGMCC No. 16713;

the LL9 strain is classified as Lactococcus Lactis subsp Lactis (CGMCC), which is deposited in China general microbiological culture Collection center (CGMCC) at 11 and 6 months in 2018 (No. 3 of Xilu 1 of Beijing, Chaoyang, the institute of microbiology, China academy of sciences), and the deposited number is CGMCC No. 16714.

2. The microbial inoculum of claim 1, wherein the microbial inoculum comprises the LCX25 strain and the LL9 strain in a ratio of 1:10 to 10:1, preferably 1:8 to 8:1, more preferably 1:5 to 5:1, further preferably 1:3 to 3:1, particularly preferably 1:2 to 2:1, most preferably 1: 1.

3. The microbial inoculum according to claim 1 or 2, wherein the microbial inoculum is in the form of a lyophilized powder.

4. A method for preparing a microbial inoculum for use in preparing a fermented vegetable protein beverage as claimed in any one of claims 1 to 3, said method comprising the steps of:

(3) centrifuging the strain fermentation liquor obtained in the step (2) and collecting bacterial sludge to respectively obtain bacterial sludge of the LCX25 strain and bacterial sludge of the LL9 strain; and

(4) mixing the bacterial sludge of the LCX25 strain and the bacterial sludge of the LL9 strain to obtain the microbial inoculum for preparing the fermented vegetable protein beverage,

5. The preparation method according to claim 4, wherein the seed medium and the fermentation medium are MRS liquid medium.

6. The production method according to claim 4 or 5, wherein the production method further comprises the steps of:

after the step (3) and before the step (4), adding a protective agent according to the volume ratio of the bacterial sludge to the protective agent 1 (3-5), fully mixing, pre-freezing overnight at-80 ℃, and preparing freeze-dried powder by vacuum freeze-drying; preferably, the protective agent is selected from one or more of trehalose, sodium glutamate, skim milk and glycerol; more preferably, the protectant is a mixture of equal volumes of trehalose, sodium glutamate, skim milk and glycerol.

7. Use of the microbial agent for producing a fermented vegetable protein beverage according to any one of claims 1 to 3 for producing a fermented vegetable protein beverage,

8. As claimed in claim 7The use of the above, wherein, in the fermented vegetable protein beverage prepared, the viable count is 10¹⁰cfu/mL-10¹²cfu/mL, more preferably 2 × 10¹⁰cfu/mL-5×10¹¹cfu/mL, more preferably 4 × 10¹⁰cfu/mL-2.5×10¹¹cfu/mL, particularly preferably 8 × 10¹⁰cfu/mL-1.25×10¹¹cfu/mL, most preferably 10¹¹The amount of cfu/mL comprises the LCX25 strain and the LL9 strain.

9. The fermented vegetable protein beverage prepared by the microbial inoculum for preparing the fermented vegetable protein beverage according to any one of claims 1 to 3,

10. The fermented vegetable protein beverage according to claim 9, wherein the number of viable bacteria in the fermented vegetable protein beverage is 10¹⁰cfu/mL-10¹²cfu/mL, more preferably 2 × 10¹⁰cfu/mL-5×10¹¹cfu/mL, more preferably 4 × 10¹⁰cfu/mL-2.5×10¹¹cfu/mL, particularly preferably 8 × 10¹⁰cfu/mL-1.25×10¹¹cfu/mL, most preferably 10¹¹The amount of cfu/mL comprises the LCX25 strain and the LL9 strain.